This invention relates to movable insulation devices for covering window and wall surfaces, and more particularly to improved seals for such movable insulation devices for minimizing or preventing air currents around, through, and within the devices from infiltration and convection.
Movable insulation adapted for use over walls and window areas of buildings to take advantage of the daily movements of the sun for efficient heating and cooling of the interiors of such buildings is beneficial and being used widely, particularly over large window areas such as those in commercial buildings and in passive solar homes. For example, in the winter it is desirable to allow the sun to shine through the windows into the interior of the building to take advantage of the radiant energy of the sun to heat the interior during the day and to place an insulation material over the window at night to minimize loss of heat from inside the building to the outside. Conversely, in the summer, it is desirable to have an insulation material in place over the window surfaces during the day to minimize heat from the sun heating up the interior of the building, and to remove the insulation material from the window area at night to allow the heat inside the building to dissipate through the windows to the cooler night air.
There have been a number of movable insulation curtains developed over the past several years that are adaptable to moving into place over windows and retraction away from the window surfaces to maximize the use of the day and night cycles of the sun to heat and cool homes and other buildings. The most popular of these devices have usually included some variation of multiple layer retractable curtains or shades which form air spaces or pockets between the layers to utilize the insulation quality of air to insulate against thermal transfer through the window surfaces. Examples of such devices include those disclosed in U.S. Pat. No. 4,039,019, issued to T. Hopper, and U.S. Pat. No. 4,187,896, issued to R. Shore. The disclosures in both of those patents recognize the importance of sealing the sides and ends of the insulation against infiltration and convection currents in order to maximize the use of the air pockets for insulation. However, while recognizing the problem, these and other prior art devices have so far continued to suffer from significant insulation value losses due to infiltration and convection currents because of inadequate seals around the sides and edges of the air pockets formed by the multiple layer movable insulation forming materials. While some of these prior art structures might be effective when hand placed in proper position over the windows, the desirability for automatic raising and lowering with a minimum of manual attention to positioning has caused effective seals for the air pockets to be an illusive goal for inventors and manufacturers for such movable insulation devices. The illusiveness of this goal is compounded when it is desired to also provide more attractive decorative fabrics for positioning over the front or interior side of the movable insulation layers to present more pleasing appearance for the interior of the buildings than is normally obtained from the light reflective fabrics and films commonly used to form the air pocket envelopes in such devices.